`sympy_json.from_jsonable()` cannot decode non-compact nodes produced by `to_jsonable(..., compact=False)`

[BenWibking]

Bug: sympy_json.from_jsonable() cannot decode non-compact nodes produced by to_jsonable(..., compact=False)

Severity

Medium

Summary

to_jsonable(expr, compact=False) returns dict-based nodes via _Encoder, but from_jsonable() only accepts list/int/float and always uses _DecoderCompact.

Impact

• Public API is asymmetric: one supported encoding mode cannot be decoded.
• Callers using non-compact mode get SympyJsonError despite valid payloads.

Affected Code

• src/jaff/sympy_json.py

Root Cause

from_jsonable() hardcodes compact decoder path.

Proposed Fix

Dispatch decoder by node type (dict -> _Decoder, list/int/float -> _DecoderCompact).

Full Patch

diff --git a/src/jaff/sympy_json.py b/src/jaff/sympy_json.py
index a16f786..81fcbb2 100644
--- a/src/jaff/sympy_json.py
+++ b/src/jaff/sympy_json.py
@@ -64,9 +64,13 @@ def to_jsonable(expr: sympy.Basic, *, compact: bool = True, include_assumptions
 
 
 def from_jsonable(obj: Any) -> sympy.Basic:
-    if not isinstance(obj, (list, int, float)):
-        raise SympyJsonError(f"Expected list/number node, got {type(obj)!r}")
-    return _DecoderCompact().decode(obj)
+    if isinstance(obj, dict):
+        return _Decoder().decode(obj)
+    if isinstance(obj, (list, int, float)):
+        return _DecoderCompact().decode(obj)
+    raise SympyJsonError(
+        f"Expected compact(list/number) or verbose(dict) node, got {type(obj)!r}"
+    )